• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.47-50
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• 2002

The numerical simulation of a 271-rod fuel assembly of nuclear Liquid-Metal Fast Reactor (LMFR) with an infernal blockage has been carried out. Internal blockage within a subassembly is addressed in the safety assessment because it potentially has very serious consequences for the reactor as a whole. Three dimensional calculations were performed using the SABRE4 computer code for the range of blockage positions and sizes to investigate the seriousness and detectability of the internal blockage. The magnitude and location of the peak temperatures together with the temperature distribution at the subassembly exit were calculated in order to look at the potential for damage within the subassembly, and the possibility of blockage detection. The analysis result shows that the 6-subchannel blockage causes large temperature rise within a assembly with practically no change in mixed mean temperature at the assembly exit.

• IEIE Transactions on Smart Processing and Computing
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• 제2권4호
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• pp.216-225
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• 2013

This paper discusses the issues regarding an abnormal V-shaped error confronting algebraic-based deconvolution process. Deconvolution was applied to an analysis of the effects of the Random Telegraph Noise (RTN) and Random Dopant Fluctuation (RDF) on the overall SRAM margin variations. This paper proposes a technique to suppress the problematic phenomena in the algebraic-based RDF/RTN deconvolution process. The proposed technique can reduce its relative errors by $10^{10}$ to $10^{16}$ fold, which is a sufficient reduction for avoiding the abnormal ringing errors in the RTN deconvolution process. The proposed algebraic-based analyses allowed the following: (1) detection of the truncating point of the TD-MV distributions by the screening test, and (2) predicting the MV-shift-amount by the assisted circuit schemes needed to avoid the out of specs after shipment.

• Current Optics and Photonics
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• 제8권2호
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• pp.170-182
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• 2024

The dimensional accuracy and consistency of a dual oil circuit centrifugal fuel nozzle are important for fuel distribution and combustion efficiency in an engine combustion chamber. A point cloud measurement method was proposed to solve the geometric accuracy detection problem for the fuel nozzle. An improved variance focus measure operator was used to extract the depth point cloud. Compared with other traditional sharpness evaluation functions, the improved operator can generate the best evaluation curve, and has the least noise and the shortest calculation time. The experimental results of point cloud slicing measurement show that the best window size is 24 × 24 pixels. In the height measurement experiment of the standard sample block, the relative error is 2.32%, and in the fuel nozzle cone angle measurement experiment, the relative error is 2.46%, which can meet the high precision requirements of a dual oil circuit centrifugal fuel nozzle.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.185-190
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• 2001

The cavitation causes suction performance and efficiency of the high-speed pump to be reduced significantly To diminish these effects, the inducer has been used. Most of the inducer is designed at a maximum efficiency point of the pump, therefore suction performance drop due to effects of flow separation and inlet inverse flow is often observed at off-design point. The objective of this study is to find out the cavitation modes at various conditions by applying event detection technique and to design an inducer reducing cavitation. The pressure fluctuations at each cavitating condition were measured at inducer inlet and outlet locations using pressure transducers, which were located 90 degrees apart from each other to identify the cavitation modes. The time-frequency characteristics were analyzed by using Choi-williams distribution. In the second part of this paper, the inducer design method which uses nominal performance characteristic and onset condition of cavitation is introduced and applied to real situation.

• 환경영향평가
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• 제4권2호
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• pp.93-103
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• 1995

This study was carried out to suggest the best statistical test to analyze the trend in monthly water quality data. Traditional parametric tests such as t-test and regression analysis are based on the assumption that the underlying population has a normal distribution and regression analysis additionally assumes that residual errors are independent. Analyzing 9-years monthly COD data collected at Paldang in Han River, the underlying population was found to be neither normal nor independent. Therefore parametric tests are invalid for trend detection. Four Kinds of nonparametric statistical tests, such as Run Test, Daniel test, Mann-Kendall test, and Time Series Residual Analysis were applied to analyze the trend in the COD data, Daniel test and Mann-Kendall test indicated upward trend in COD data. The best nonparametric test was suggested to be Daniel test, which is simple in computation and easy to understand the intuitive meaning.

• 한국동물위생학회지
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• 제18권3호
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• pp.36-41
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• 1995

This study was conducted to determine the serum antibodies against toxoplasma in bovine from gyeongnam district by latex agglutination(LA) test. LA test was carried out with Toxo-MT kit(Eikon chemical co). The result obtained were summerized as follow： 1. Positive rates of toxoplasma antibodies in 1,488 bovine sera was 5.0%(75 cases) by LA test. 2. The toxoplasma antibody detection rates against 823 korean cattle and 865 dairy cattle were 1.8%(11 cases) and 7.4%(64 cases) respectively. 3. In LA test serum antibody titers in 75 positive sera were shown as 54 cases(72.0% in 1：32, 9(12.0%) in 1：64, 7(9.4%) in 1：128, 3(3.40%) in 1：256, 1(1.3%) in 512 and 1(1.3%) in 1：2,048 respectively. 4. Positive rates of toxoplasma antibodies in cattls sera from each area were 0.2∼22.0%.

• 한국항행학회논문지
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• 제15권3호
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• pp.471-477
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• 2011

CCTV 카메라는 비디오 감시분야나 화재검출 시스템 등에 다양하게 응용되는 바, 본 논문에서는 고정된 카메라에서 영상 정보를 취득하여 비디오 시컨스를 분석한 후 화재정보를 검출하는 방법을 제안하였다. 연속영상의 배경과 화재정보를 공간적으로 검출하고, 시공간적으로 편차가 급격하게 나타나면 화재 발생 인자로 결정하여 실험을 수행하였다.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.484-492
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• 2012

The TMS(Thermal Management System) heater in a fuel cell vehicle has been developed to prevent a decline of fuel cell durability and cold start durability. Main functions of the COD(Cathode Oxygen Depletion) heater are depletion of oxygen in a cathode as heat energy and consumption of electric power for rapid warming up of a fuel cell stack. This paper covers subjects including the design specification of a heater, heater controller for detection of overheat and reliability assessment including coolant pressure cycle test of a heater. To verify the design concept, burst pressure and deformation analysis of plastic housing were carried out. Also, temperature distribution analysis of heater surface and coolant inside of housing were carried out to verify the design concept. By designing the plastic housing instead of a steel housing, the 30% weight lightening and 50% cost reduction were attained. A module-based design of a TMS system including a heater or reducing the watt density of a heater is a problem to be solved in the near future work.

• 한국소음진동공학회논문집
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• 제26권2호
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• pp.203-209
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• 2016

According to the wear detection history for the steam generator tubes in the nuclear power plant, the outer tubes inside the steam generator have more problems on the flow-induced vibration than inner tubes. Many researchers and engineers have used a specified added mass coefficient for a given tube array during the design stage of the steam generator even though the coefficient is not constant for entire tube in cylindrical shell. The aim of this study is to find out the distribution of added mass coefficients for each tube along the radial location. When numbers of tubes inside a cylindrical shell are increased, values of added mass coefficients are also increased. Added mass coefficients at outer tubes are less than those of inner tubes and they are decreased with increasing the gap between the outermost tube and the cylindrical shell. It also turns out when the gap between the outermost tube and the cylindrical shell approaches infinite value, the added mass coefficient converges to an asymptotic value of given tube array in a free fluid field.

• Journal of Ecology and Environment
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• 제29권4호
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• pp.331-335
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• 2006

We investigated the distribution of three anuran species, Three-striped pond frogs (Rana nigromaculata), Bullfrogs (Rana catesbeiana), and Narrow-mouthed toads (Kaloula borealis), in an administrative district, Haenam Gun, Junnam Province, Korea using volunteer call surveys. Twenty-eight volunteer call surveyors were assigned to each $2{\times}2km^2$ survey plot. Call surveys on whether the species are present or not were conducted for 5 minutes between 30 minutes after sunset and the midnight on rice fields and ponds from 10 April to 28 August in 2005. Depending on species, call surveys were carried out at seven to 28 plots with average 8.4 to 10.7 visits per the plot. We calculated the detection probabilities and occupancy rates of the three species using four models with three covariates: temperature, humidity, and the amount of water at the habitat. The model average detection probabilities of three anuran species of R. nigromaculata, R. catesbeiana, and K. borealis were 0.53, 0.74, and 0.41 respectively, and the site occupancy rates of them were 0.93, 0.94, and 0.86 respectively. Our results indicate that R. nigromaculata, R. catesbeiana, and K. borealis are common in Haenam Gun.